ABSTRACT
The Vajont river valley is located in the Italian Alps, less than 100 km to the north of the city of Venice. In a region where the river passes through a narrow gorge of dolomitic limestones from the Jurassic, a 276-m high concrete arch dam was built between 1957 and 1960. In 1963, the dam reservoir was filled in stages, under constant monitoring. This monitoring was required, following a potential instability of the slopes on the left bank, consisting of a slow displacement, which had already been observed during the first partial filling stage, in 1960. Along the failure surface, corresponding to formations from the Upper Jurassic, clays and very plastic marls have been identified. The safety factor of the soil masses that had previously experienced such landslides is frequently quite small, and in some cases marginally above 1.0.
